It has always seemed to me possible, and even probable, that there would be a resurrection of Islam and that our sons or our grandsons would see the renewal of that tremendous struggle between the Christian culture and what has been for more than a thousand years its greatest opponent.

So writes Belloc, as published in 1938. Before considering the heresy and the history both before and since he wrote these words, perhaps it is worth considering the situation in Muslim lands at the time he was writing.

1938

After the Great War, what was left of Mohammedan power even in hither Asia, let alone Constantinople, was only saved by the violent quarrels between the Allies.

In 1938, almost all Muslims lived in lands controlled and occupied by a European power: virtually all of North Africa; all of the Middle East except Turkey (you might also except Saudi Arabia, but must recognize the British position in their oil); much of Central Asia; finally, the Asian sub-continent.

It was in this environment of the Muslim's weakest point since its founding that Belloc foresaw the rise once again of a Muslim threat to Europe.

The History

Belloc offers a brief history of the rise and fall of Islam as a political power and empire:

Islam – the teaching of Mohammed – conquered immediately in arms. Mohammed's Arabian converts charged into Syria and won two great battles…

They quickly overran Egypt and Northern Africa, Asia Minor, finally crossing the Straits of Gibraltar into Spain. By 732 – less than 100 years after their first victories – Muslim armies reached as far as Northern France. They were thrown back to the Pyrenees, but continued to hold most of Spain.

We know of the Crusades called by the Pope. These were not called in a vacuum; they were called in reaction to the violent conquest of Christian lands in the Middle East. Brief successes followed by ultimate failure.

If the first Crusaders had had enough men to take Damascus their effort would have been permanently successful.

But they had only enough men to hold the seacoast of Palestine (I expand on this history here and here, also thanks to Belloc). Perhaps a similar reason as to why Syria is so important today.

The battle was fought by the Habsburg Monarchy, the Polish–Lithuanian Commonwealth and the Holy Roman Empire, under the command of King John III Sobieski against the Ottomans and their vassal and tributary states. The battle marked the first time the Commonwealth and the Holy Roman Empire had cooperated militarily against the Ottomans, and it is often seen as a turning point in history, after which "the Ottoman Turks ceased to be a menace to the Christian world".

The Battle of Zenta…on the east side of the Tisa river, was a major engagement in the Great Turkish War (1683–1699) and one of the most decisive defeats in Ottoman history.

This battle ended Ottoman control over large parts of Central Europe. And from this point, we come to 1938 and the aforementioned European control over the vast majority of lands populated by Muslims, as Muslims gradually lost the race to Europeans in the material things necessary to wage war.